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     Welcome to my personal homepage! If you are here to use the X-ray source quick viewer that I create for the Chandra and XMM-Newton source catalogs, please click here.

  

  Research Assistant Professor
  Department of Physics & Institute for the         Study of Earth,  Oceans, and Space

   University of New Hampshire
  245C Morse Hall
 
8 College Road
  Durham, NH 03824-2600
  U.S.A. 
  dacheng@dachenglin.com
  www.dachenglin.com

Educational Background:

  • 2009 Ph.D. - Physics, Massachusetts Institute of Technology
  • 2003 B.S.   - Geophysics, University of Science and Technology of China

Research Interests:

  • The accretion process around black holes across mass scale: black-hole X-ray binaries, ultra-luminous X-ray sources, AGN
  • Tidal disruption events (Tidal disruption of stars by otherwise dormant supermassive black holes)
  • Search for intermediate-mass black holes of mass 100--100,000 solar mass
  • Catalog studies
  • The accretion process in neutron-star low-mass X-ray binaries and properties of dense matter

Recent News: 

****Black Hole Meal Sets Record for Duration and Size
  • A supermassive black hole in a small galaxy 1.8 billion light years away has been partaking in a decade-long binge of a star.

  • This is known as a tidal disruption event and happens when an object gets too close to a black hole and is torn apart by gravity.

  • Other similar events have been seen before but this one is much longer, representing an unusually massive meal.
   

****A Wandering Massive Black Hole Caught Shredding a Star

wandering black hole XJ1417+52

Within this optical light image from the Hubble Space Telescope, the massive black hole and its host galaxy are in the box in the upper left. The inset on the left is a close-up view of the galaxy, with what may be the source associated with this black hole circled. The inset on the right is Chandra’s X-ray image of the massive black hole.

More information, click here. The paper can be found here.


***Strong Heartbeat-Like Signals from Gorging Supermassive Black Hole



The XMM-Newton space observatory from European Space Agency detected an extremely rare heartbeat-like X-ray pulsation signal from a black hole of 100,000 times that of the sun at the center of a galaxy at a distance of 1.7 billion light years. The black hole was gorging on matter at the highest possible rate. Such signals are common in small black holes with mass less than 20 times that of the sun, but are very rare among supermassive black holes. Only two cases were reported before, but with much weaker signals.

The pulse rate is once per 3.8 hours (see the figure above), much lower than those in small black holes, just like smaller animals have higher heart rates!

More information, click here. The paper can be found here.



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